This invention relates to the packaging of sheet metal parts and to the assembly of such parts to a workpiece. There herein disclosed embodiment of the invention relates to the packaging of the two parts of a keyboard switch and the assembly of the parts to a circuit board. However, it will be apparent that the principles of the invention can be used for other types of sheet metal parts which are to be assembled to a workpiece.
The widespread and increasing use of circuit boards has given rise to a need for relatively small inexpensive switches which are mounted on the circuit board and which are momentarily closed by an operator. These so called keyboard switches each comprise a fixed contact which is rigidly mounted on the circuit board and a normally open movable spring contact which is spaced from the fixed contact and which can be resiliently moved towards, and into engagement with, the fixed contact when the switch is closed.
It is common practice to manufacture the fixed and movable contacts or keyboard switches from metal strip by stamping and forming operations and it is also common practice to assembly the switch parts to the circuit board in two separate assembly operations. For example, during the manufacture process, the circuit board is carried to a first insertion apparatus at which fixed contacts are inserted into the board at all the locations at which a switch is required. The board is then carried to a second assembly machine at which the spring contacts are assembled to the board adjacent to each of the fixed contacts. It will be apparent that this two step assembly process is relatively costly and time consuming and, in fact, the cost of providing the switches on an inexpensive hand held calculator constitutes an inordinately high percentage of the total manufacturing cost.
The instant invention is directed to the achievement of improved packaging methods which will facilitate, and reduce the assembly cost of keyboard switches for circuit boards. The invention is also directed to the achievement of improved handling and shipping methods for keyboard switch parts, and other small parts, which give rise to other benefits as will be described below.
It is accordingly an object of the invention to provide an improved packaging method for small sheet metal parts. A more specific object is to provide an improved packaging method for the two parts of a keyboard switch. A further object is to provide an improved method of assembling sheet metal parts to a workpiece. A still further object is to provide an improved method of assembling the two parts of a keyboard switch to a circuit board.